Aftermarket fuel injection, no start issue

[Posimoto]

I know we have at least 3 members with aftermarket FI so I thought I would address a no start issue in hope that it may help others down the road.

78 CJ7, 360 Howell Fuel Injection

After power washing my CJ I jumped in to start it and it turned over but wouldn't fire.
My fuel gauge isn't working, and with the long ride to and from FF to Swanzy, plus a day of wheeling, I thought I was out of fuel (fuel pump working).
Added 3 gallons, still wouldn't fire, fuel pump working.
I opened the hood and noticed water near the ignition module.
I forgot the cheap ass glass fenders don't have a a splash guard built into the fenders like to metal original ones do (located on the fender inside the hood).
Anyways, removed the air filter and cranked the engine, fuel was pulsing out the injectors, but not steady, instead they were alternating. This is not normal.
Is this an ignition problem, or a tach filter/ecm problem?
There is an easy way to find out.
Remove the white tach wire from the negative side of the coil.
With a test light hooked to the positive post of the battery, key on, touch and remove the test light to the end of the white tach wire. Each time you touch and remove the test light the injectors should spit fuel (simulated a spark).
If it spits fuel you have an ignition problem.
If it does not you have a tach/emc problem

My injectors did not spit fuel.
The test told me I had a problem with my tach filter or ecm.
The next test would tell me if it was the tach filter or ecm
With the test light still hooked up, and key on, touch and remove the test light on pin B5 at the ecm.
Although you won't see the injectors fire working inside the rig you will hear the pump running. If the pump runs the issue is the tach filter. If the pump does not run you have a bad ecm.
My pump ran.
Results, I had moisture on the ignition module connectors and when I tried to start the engine it caused a voltage spike that toasted the tach filter. I'm blaming it on the glass fenders 

Howells sells tach filters for $50 but I'm looking into ways I can delete the filter by going with a 7 pin gm ignition module. I have both the 4 and 7 pin gm IM I grab when I was last at the boneyard. Stock, msd, and dui have to run the tach filter. I have to look into this a bit more.

Hope this helps.

 



 

[jps4jeep]

Good luck, how did water get in? I just looked at the tbi 350 sitting in my garage and it has a weather tight type Delphi connector?

[Posimoto]

Good luck, how did water get in? I just looked at the tbi 350 sitting in my garage and it has a weather tight type Delphi connector?

I opened the hood and noticed water near the ignition module.
I forgot the cheap ass glass fenders don't have a a splash guard built into the fenders like to metal original ones do (located on the fender inside the hood).

Results, I had moisture on the ignition module connectors and when I tried to start the engine it caused a voltage spike that toasted the tach filter. I'm blaming it on the glass fenders 

The tach filter is located in the harness about 8" from the ecm in shrink tube = safe from water. 

[Posimoto]

I found a tach filter that will work, Autometer part # ATM-9116 $25 shipped (howell wants $50).
I could also run a 7 or 8 pin gm module in parallel with a 4 pin module to act as the filter for the ecm.
If I were to keep the rig I would ditch the stock ignition module, distributor, and coil for a HEI distributor, lock the mechanical advance, and go with the 7 pin module for timing control instead of the current fuel only system.

[Posimoto]

Autometer part # ATM-9116 $25 shipped

After talking to summet tech concerning a tach filter specifically for my use with my FI they recommended and assured me the above part # would work. As soon as I opened the package I could see it wouldn't work for me. I had a choice of going electronic timing and deleting the tach filter, or buy howell's tach filter. I decided to buy the tach filter so I wouldn't miss the next trail ride.

Wired in the filter and the engine started as it should.



I removed the jacket from the tach filter, resistors look to be 20k, 10k, and 1k from what I can tell by the bands. A chip, and possibly a zero resister, I'm not sure what the last piece is.



The alternative would be to lock down the stock distributor, wire in an 8 pin gm module, and run 4 wires back to the ecm. You would also need to remove the stock resistor wire and reprogram the chip as well. Reprogramming the chip may have held me up so I went with the tach filter for now. I also took the opportunity to clean up the under dash wiring while I was there.


 

[Axle]

very good